In recent history, tissue ablation procedures have employed a “dry” electrode. Dry electrode tissue ablation systems, such as TUNA systems, typically have needle electrodes coupled to a trigger mechanism for deploying the needles. The needles are coupled to a power generator. A manual switch is typically engaged to complete a circuit allowing ablative energy to flow from the power generator to the tissue via the needles. Thus, for a typical tissue ablation device to deliver ablative energy to a tissue, an end use of the device performs at least two separate steps: 1) engaging a trigger mechanism to deploy needles and 2) engaging a switch to supply ablative energy from the power generator to the tissue via the needles. More simplified systems have not been described.
Rather, more complex systems in the form of “wet” electrode systems have been proposed. While more complex, wet electrode systems have been proposed to address some shortcomings of dry electrode systems. More particularly, the amount of power delivered and speed of lesion formation in dry electrode approaches is limited by high impedance at the electrode-tissue interface. To minimize this issue, it has been proposed to pump saline through the electrode to create a “wet” electrode. Saline increases the conductivity of the tissue to be treated, allowing for increased efficiency of tissue ablation. However, proposed wet electrode tissue ablation systems may require additional controls and equipment for delivering the saline, making wet electrode tissue ablation, such as TUNA, more complex to perform than traditional dry electrode tissue ablation.